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12. A uniform disk rotates at a fixed angular velocity on an axis through its center normal to the plane of the disk, and has kinetic energy E. If the same disk rotates at the same angular velocity about an axis on the edge of the disk (still normal to the plane of the disk), what is its kinetic energy?
(a) 1/2E
(b) 3/2E
(c) 2E
(d) 3E
(e) 4E
Answer: D
Relevant Equations: KE= 1/2 I x w^2, I=MR^2
Attempt at Solving: Io=MR^2, In=4MR^2, thus KE=4 (1/2 I x w^2)= 4E
Can someone please explain why the answer is 3E? I really appreciate your assistance! Thanks!
(a) 1/2E
(b) 3/2E
(c) 2E
(d) 3E
(e) 4E
Answer: D
Relevant Equations: KE= 1/2 I x w^2, I=MR^2
Attempt at Solving: Io=MR^2, In=4MR^2, thus KE=4 (1/2 I x w^2)= 4E
Can someone please explain why the answer is 3E? I really appreciate your assistance! Thanks!